Heart HealthJan 24, 2026 6 min read
Heart-Rate Zones, Explained Without the Jargon
Z2 builds your engine, Z5 sharpens its edge. A practical guide to training where it matters.
By Elements84 Medical Editorial Team
Read Heart health · Training zones
Heart Rate Calculator
Target heart-rate zones for cardio training.
Your details
Estimated max HR
187bpm
Training zones (Karvonen)
Z1 — Recovery
Active recovery, warm-up, easy aerobic.
124–136 bpm
Z2 — Base / Endurance
Aerobic base — burn fat efficiently, build engine.
136–149 bpm
Z3 — Tempo
Moderate effort, sustained pace.
149–162 bpm
Z4 — Threshold
Hard intervals at lactate threshold.
162–174 bpm
Z5 — VO₂ max
All-out efforts, short intervals.
174–187 bpm
How max HR is estimated
We use the Tanaka equation (208 − 0.7 × age), considered more accurate than the classic "220 − age".
Why Karvonen?
Instead of straight percentages of max HR, Karvonen anchors zones to your heart-rate reserve (max − resting) — more individual and respects your current fitness.
The five zones, in one minute
Z1 recovery · Z2 aerobic base · Z3 tempo · Z4 lactate threshold · Z5 VO₂ max. Most athletes spend 70–80% in Z1–Z2 and only short bursts in Z4–Z5.
Limitations & caveats
- HR-max estimates have ±10 bpm individual variation.
- Beta-blockers materially lower HR-max.
- Best-measured resting HR is on waking, lying still.
- Karvonen assumes normal sinus rhythm.
- Elite athletes should use graded exercise tests.
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How we ground the Heart Rate
Grade A · Clinical guidelines & meta-analysesLast reviewed Nov 1, 2025
Named clinical guidelines
- Tanaka formula (2001) — more accurate than 220 − age
- Karvonen method — anchors zones to heart-rate reserve
References
- Tanaka H et al. — Age-predicted maximal heart rate revisited· JACC
- ACSM Guidelines for Exercise Testing and Prescription· American College of Sports Medicine